The present invention generally relates to a computer system. More particularly, the invention is concerned with a method and a system for controlling parallel execution of jobs and/or job steps, which method and system are advantageously and profitably suited for execution of jobs including job steps executable in parallel.
With the conventional techniques directed to reexecution of a job (i.e., restart of execution of a job after abnormal interruption thereof), such arrangement is adopted that a job execution which ended at a given job step due to occurrence of abnormality in that job step or for other reason can be restarted from that given job step, as is disclosed, for example, in JP-A-63-211033. More specifically, upon reexecution of a job ended abnormally, the job is reregistered, whereupon on the basis of information indicating to which step the job execution has been completed, the job is executed while skipping the job steps to one preceding to the job step at which abnormality occurred, to thereby allow the job to be reexecuted, starting from that preceding step.
On the other hand, in conjunction with parallel execution of job steps, such a system or scheme has already been proposed in conjunction with a job composed of a plurality of job steps that information of designation indicating whether or not a given job step can be executed in parallel with other job step belonging to the same job is affixed to a relevant control statement commanding the job step execution, to thereby allow a plurality of job steps to be executed concurrently, as is disclosed, for example, in JP-A-6-202881.
The first mentioned job reexecution technique (JP-A-63-211033) can certainly ensure the function for recovering or restoring the job whose execution ended with abnormality. However, no consideration is paid to reduction or decrease of the time required for execution of the job. Moreover, with this conventional technique, it is impossible to execute a plurality of same job steps concurrently in parallel with one another, giving rise to another problem.
On the other hand, in the case of the second mentioned prior art (JP-A-6-202881), parallel execution can be performed only for those job steps which differ from one another and which belong to a same job, and no consideration is paid to parallel execution of a plurality of same job steps, presenting thus a problem that the time taken for execution of job step can not be shortened.